Containers for beverages such as milk, cream, other dairy products, juices, and the like, are conventionally constructed from the thermoplastic coated paperboard. Typically, these containers include a top end closure with a folded roof structure adaptable to providing a readily available pouring spout when the contents of the container are to be dispensed.
Coated paperboard blanks for constructing such a container are made on converting machines similar to those disclosed by Monroe et al U.S. Pat. No. 2,682,208 and Earp U.S. Pat. No. 3,731,600. After construction, the blanks are processed by forming, filling and sealing machines, such as those disclosed by Monroe et al U.S. Pat. No. 3,303,761, Allen Patent No. 3,918,236, Egleston patent No. 3,398,659 or Young U.S. Pat. No. 4,193,833, to produce the formed, filled and sealed containers of the type referred to above and shown and described in Egleston et al U.S. Pat. No. 3,270,940, or Lisiecki U.S. Pat. No. 4,422,570.
While this type of container has been generally satisfactory for liquid products, it is desirable to utilize a similar square or rectangular thermoplastic coated paperboard container for frozen juices with a modified top closure arrangement which is adaptable to being fully opened, in lieu of using a conventional cylindrical paperboard container with a removable metal or solid plastic top cover. Such a modified top closure arrangement is desirable also for containing and providing access to "spoonable" products, such as yogurt and puddings. One example of a satisfactory top closure of a substantially fully openable type is shown and described in Lisiecki U.S. Pat. No. 4,397,415. A further example of a satisfactory top closure of a completely fully openable type is shown and described in Lisiecki U.S. Pat. No. 4,702,407.
An example of a satisfactory flat top container having a separate cover member is shown and described in Lisiecki patent application No. 225,382.
Young et al U.S. Pat. No. 3,756,500 discloses a corner construction for membrane sealed cartons, including a horizontal score line between the body side panels and the respective end panels which differs from the usual blank arrangement in that at each intersection with a vertical score line, short diagonal lines converge upwardly (away from the adjacent body panels) to an apex at the vertical score line. This results in raised contact areas at each corner once all four end panels are outfolded in a horizontal plane relative to the vertically erected side panels, to provide a frictional area contact at each corner for a sealing membrane applied thereto.
Humphries U.S. Pat. No. 4,304,352 discloses a tray with gusset corners covered by a lid. In this arrangement, the flange sections extend laterally outwardly from their respective side panels, with corners consisting of two triangular gussets folded together and then folded onto and sealed against a side wall.